29.11.2022 | Materials science

Cosmically inspired: super magnet without rare earths

Materials researchers from the Austrian Academy of Sciences, in cooperation with colleagues from Cambridge University, UK, have found a way to produce the mineral tetrataenite, previously only known from meteorites, in the laboratory. The material could be used to create the enormously strong magnets that are used, for example, in electric cars or wind turbines without the use of rare earths. This would reduce environmental damage and resource dependency.

© Klaus Pichler/ÖAW

“Tetrataenite is an iron-nickel mineral with a unique tetragonal structure that was first identified in iron meteorites. The structure of tetrataenite normally only arises when an iron-nickel mixture cools extremely slowly after its formation, at a rate of less than 0.01 degrees Celsius per year,” explains Baran Sarac from the Erich Schmid Institute of Materials Science of the OeAW at the University of Leoben. Sarac and his colleagues have now managed to create tetrataenite by adding small amounts of phosphorus and carbon to a melt of iron and nickel in the laboratory. The magnetic assessment of the material was then taken over by colleagues from the University of Cambridge, with whom the work was recently published in the journal “Advanced Science”.

Revolution for electric motors

“We were able to accelerate the formation of tetrataenite by 11 to 15 orders of magnitude compared to the process that occurs in meteorites. Under a vacuum we were able to cast cylinders 1-3 millimeters long that cool down in a few milliseconds, without any special treatment,” Sarac says. The special thing about tetrataenite is its structure-related magnetic properties. The mineral is a strong permanent magnet, with its energy product reaching values similar to those of rare earth alloys.

For applications that require powerful magnets in tight spaces, such as electric motors and wind turbines, neodymium and other rare earths are currently unrivaled. This is problematic because the mining of the corresponding ores involves enormous effort and great environmental impact. In addition, the market for the materials is served almost exclusively by China, which could lead to problems with security of supply in the longer term. With the new method, tetrataenite can be produced quickly, inexpensively and with manageable effort and could thus become a future driver for the electrification of transport and the expansion of wind turbines.

“The relatively simple manufacturing process could allow us to achieve industrial-scale production in a relatively short time. That would of course be appealing for the production of powerful magnets without rare earths. We are already in contact with start-ups and large companies that are interested in our method,” Sarac says. The team in Leoben has applied for a patent for the new technology in cooperation with the University of Cambridge and the OeAW.



„Direct Formation of Hard-Magnetic Tetrataenite in Bulk Alloy Castings“, Yurii P. Ivanov, Baran Sarac, Sergey V. Ketov, Jürgen Eckert, A. Lindsay Greer, Advanced Science, 2022
DOI: https://doi.org/10.1002/advs.202204315